Q to Michael Rowling, COO of ProtoKinetics: ProtoKinetics is recognized as a major actor in the gait analysis domain of and, with its core product the Zeno walkway, powered by PKMAS software. Which aspirations and goals drove you to create an instrumented version of the FSST?

Our technology is well established and offers accurate, digestible, and powerful data output for gait assessments. It’s incredibly rewarding and humbling to discover each week new peer-reviewed articles from clients all over the world.  ProtoKinetics has succeeded in making a name for ourselves, but few people know that “Proto” stands for protocols.  Since ProtoKinetics’ inception, our goals have always been to drive innovation by implementing and automating standardized clinical tests or protocols, revealing additional insights. Gait is an important metric, in fact, it’s commonly referred to as the 6th vital sign. However, a complete picture of a person’s mobility performance requires more data, specifically more objective data on dynamic stability, weight shifting, and weight acceptance. Therefore, we felt certain that using our Zeno pressure data and the power of PKMAS to investigate the varied movements of the FSST, a rapid, multidirectional stepping test, had the potential to assist clinicians to guide interventions and further assessments.


Q to Dr. Arnaud Gouelle: With the recent boom of wearable sensors, there is a trend to instrument all standard clinical tests, but is it always valuable to do so? Why was the FSST a valuable test to automate and how did you develop key outcomes for the iFSST?

That is really an interesting question in this hypermodern era. To instrument a test with technology is not the hardest part and anyone can do it. Add a dozen of sensors on a person, the sensors will measure the events and changes and will provide you numbers. Everything can be measured, but everything cannot get meaning and value for the clinician and the patient, who are the person we want to help. Transforming these sensor signals into meaningful parameters is always the real challenge and, before moving into the data and algorithms, there is a considerable background work to understand movement subtleties and define the best approach for an analysis. You cannot automate or analyze a movement if you do not fully understand.

The FSST was a nice challenge on this part because motor control and intentionality have effects on the way it is performed. Clearly, differentiation of left and right stances is essential to decompose the FSST and a strength of the Zeno walkway in this project was the ability to use pressure data under each foot, when for example, a single force plate would give you only global forces and center of pressure.  The iFSST provides complementary information about the durations, the foot sequence and weight shifting which end to end give better keys to understand the individual’s performance.

However, as we highlighted in our recent article with Dr. Jason Highsmith at University of South Florida, the Four Square Step Test has been thought of as a simple clinical test for dynamic balance and mobility assessment, but it is also an agility test. “In this situation, some specific changes in the variables can both be considered as worsening in some individuals and as a contributing factor to the performance in others.”


Q to Dr. Staci Shearin: Congratulations for your recent paper which investigates the iFSST among individuals after stroke, with MS or PD, and in older adults, and identifies significant differences between groups. Other variables from gait analysis or PRO have surely been recorded for this cohort. In which sense the iFSST related with these outcomes or brought different level of information?

Thank you!  In addition to the iFSST, we assessed gait measures on the Zeno walkway as well as other outcome measures regarding balance and lower extremity strength. The iFSST in particular, showed some interesting relationships with gait especially in terms of step length and gait speed. We are working on disseminating this information in an additional paper! In addition to the standard gait parameters, we think the iFSST provides novel information about direction change and possibly even cognition! I believe the balance information provided by the iFSST is an excellent complement to assessing gait in the clinic.


Q to Dr. Staci Shearin: Prior to using the iFSST with the Zeno Walkway, did you perform the FSST test with a patient population? If so, how did you use the FSST to guide your therapeutic choices? In you first exposure to the iFSST do you see ways these unique measures can enhance your use of the FSST test?

Yes, we often have used the FSST in our clinic and for research purposes! Prior to the iFSST, we were only able assess the total time and compare it to the normative values or cut-off scores for fall risk. This information is extremely critical to identifying safety concerns regarding dynamic balance is a quick manner. However, with the iFSST we were able to get detailed information that provided an insight into right vs left lower extremity stability, issues with weight shifting, and a clearer picture of problems within the test that was not objectively identified before. In particular, the changes in main support provide valuable information on coordination, stability, and efficiency during the test. I think this could be very valuable in assessing the impact of interventions for individuals with balance impairments.


Q to Dr. Staci Shearin: Moving forward, do you expect to continue working with the iFSST and how do you see it being utilized?

We are definitely interested in studying the response/changes in the iFSST parameters in response to clinical interventions. This could be a very interesting and objective tool for assessments, clinical progress and response to interventions.